A light-dimming device for dimming an illumination load is known (e.g., Patent Literature 1).
The light-dimming device described in Patent Literature 1 includes a pair of terminals, a control circuit, a control power supply configured to supply control electric power to the control circuit, and a dimming manipulation section configured to set the dimming level of the illumination load.
Between the pair of terminals, the control circuit and the control power supply are connected in parallel to each other. Moreover, between the pair of terminals, a series circuit of an alternating current (AC) power supply and an illumination load is connected. The illumination load includes a plurality of light emitting diode (LED) devices and a power supply circuit configured to light the LED devices. The power supply circuit includes a smoothing circuit of a diode and an electrolytic capacitor.
The control circuit includes a switch which enables phase control of an AC voltage to be supplied to the illumination load, a switch driver configured to drive the switch, and a controller configured to control the switch driver and the control power supply.
The control power supply is connected in parallel to the switch. The control power supply converts the AC voltage of the AC power supply into control electric power. The control power supply includes an electrolytic capacitor configured to store the control electric power.
The controller is supplied with the control electric power from the control power supply via the electrolytic capacitor. The controller includes a microcomputer. The microcomputer performs reverse phase control in accordance with a dimming level set by the dimming manipulation section to interrupt power supply to the illumination load during a time period of each of half cycles of the AC voltage.